As a heater, a heater described in, for example, Japanese Unexamined Patent Publication JP-A 2015-18625 (hereinafter, also referred to as “Patent Literature 1”) is known. The heater described in Patent Literature 1 includes a ceramic body and a heat generating resistor provided within the ceramic body. The heat generating resistor has two straight line sections and a folded section which connects the two straight line sections. In recent years, improvement of a rate of temperature rise has been demanded of a heater.
In a cross section of the heater described in Patent Literature 1 perpendicular to an axial direction of the two straight line sections, the two straight line sections each have a shape having a major axis and these major axes are in a parallel relationship. Furthermore, a centroid of the two straight line sections is located on a line dividing the ceramic body in half. Owing to this, heat generated from the two straight line sections is prone to be confined in an intermediate portion between the two straight line sections in the ceramic body. As a result, it has been difficult to improve a rate of temperature rise of a surface of the ceramic body that is to come in contact with an object to be heated.